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Abstract:

A medical access device for creating an access to a body for minimally
invasive intervention has a hollow body assembled from at least two parts
having longitudinal extending edges. Each part has a distal body portion
and at an angle to the latter a proximal body portion. A locking
mechanism locks the assembled proximal hollow body portions. The locking
mechanism has a hook projecting from an edge of a proximal body. A nose
of the hook can enter from proximal to distal in a recess in an edge
joining said edge having said hook.

Claims:

1. A medical access device for creating an access to a body for a
minimally invasive intervention, comprising a hollow body, assembled from
at least two parts having longitudinally extending edges, said at least
two parts being assembled along its respective longitudinally extending
edges, each part having a distal body portion and, at an angle to the
latter, a proximal portion, said distal body portions, when assembled
along its edges, result in a distal body with laterally outwardly
standing proximal body portions, and when moving said laterally outwardly
standing proximal body portions inwardly together along said edges along
a curved transition area, a proximal hollow body results with laterally
outwardly standing distal body portions, a sealing cap fitted onto a
proximal end of said proximal hollow body, and a locking mechanism
locking said assembled proximal hollow body portions, wherein said
locking mechanism having at least one hook projecting from an edge of a
proximal body portion, said hook having a nose extending from proximal to
distal, and having a recess in an edge joining said edge having said
hook, said recess being cut into said edge opposite to said hook and said
recess opens to said hook, a shape of said recess is in that, when moving
said proximal parts inwardly together by rolling said edges to be joined
in a first direction along said curved transition area, said nose of said
hook enters said recess from proximal to distal without a relative
movement between hook and proximal part having said hook, and said recess
blocks a movement of said hook out of said recess in a direction
perpendicular to surfaces of said edges, thereby blocking a pulling away
of joined edges, and wherein said nose moves out of said recess, without
a relative movement between said hook and said proximal part having said
hook, when moving said joined proximal parts by rolling it in a second
direction counter to said first direction along said curved transition
area.

2. The medical device of claim 1, wherein said hook having said nose
projects from a longitudinal edge of a proximal body portion, which nose
can be moved in and out of a recess in an opposite longitudinal edge of a
proximal body to be joined.

3. The medical device of claim 1, wherein said recess has an undercut
behind which said nose of said hook can be moved.

4. The medical device of claim 1, wherein said nose is shaped in such a
way, when it has moved into said recess, it lies flush in said recess.

5. The medical device of claim 1, wherein said hook is designed as a
projection on a longitudinal edge of a proximal body portion, a thickness
of said hook corresponds at least to a wall thickness of said proximal
body portion.

6. The medical device of claim 1, wherein said recess is designed as a
material cutout through an entire wall thickness of said longitudinal
edge of said proximal body portion to be joined with said body portion
having said hook.

7. The medical device of claim 1, wherein said hook is designed as a
separate part which is embedded into said proximal body portion.

8. The medical device of claim 1, wherein said recess being formed in a
separate part that is embedded into a wall of said proximal body portion.

9. The medical device of claim 1, wherein said at least one hook is
arranged in said curved transition area.

Description:

BACKGROUND OF THE INVENTION

[0001] The invention relates to a medical access device for creating an
access for a minimally invasive intervention, with a hollow body
assembled from at least two parts along the longitudinal edges thereof,
wherein each part has a distal body portion and, at an angle to the
latter, a proximal body portion, and wherein projections present on the
longitudinal edges engage with recesses on an opposite longitudinal edge.

[0002] A medical device of this kind is known from EP 2 228 024 A1.

[0003] In a first position, the at least two parts are assembled such that
the respective distal body portions form an approximately rod-shaped
distal body. In this position, the medical device can be placed, for
example, on an incision in the skin of an abdominal wall and can be
driven through the abdominal wall into the abdominal cavity. In this
state of assembly, the medical device thus functions as a trocar sleeve
of a trocar, which is used for a laparoscopic intervention.

[0004] The proximal body portions, which are each angled laterally in
relation to the respective distal body portions, extend to the sides from
this assembled distal body and project above the skin or the abdominal
wall. These proximal body portions are then pivoted such that they join
together to form a proximal hollow body. In this process, the proximal
body portions present in the abdominal space are pivoted laterally away
from each other. A sealing cap is then fitted onto the proximal hollow
body.

[0005] In this pivoting movement, the mutually opposite longitudinal edges
of the bodies roll along each other in the curved transition area between
the respective distal body portion and the respective proximal body
portion. This rolling movement is guided by projections present on the
longitudinal edges, which projections can engage in corresponding
recesses on an opposite longitudinal edge.

[0006] These projections can be knobs or tongues that engage in
corresponding depressions or grooves in the opposite longitudinal edges.

[0007] This arrangement of knobs or groove and tongues not only guides
this rolling movement but also prevents the two parts from separating
from each other transversely with respect to the surface of the
longitudinal edges.

[0008] At the same time, the intensive interlocking of these toothing
features ensures a relatively gas-tight seal along the longitudinal edges
of the joined-together proximal body portions. In this way, it is
possible, as is customary in laparoscopic surgery, to introduce an
insufflation gas into the abdominal space through the proximal hollow
body, which is formed by the two proximal body portions and is sealed off
proximally by the cap, in order to inflate the abdominal space.

[0009] A particular advantage of the device is that a surgical instrument
pushed through the latter can be tilted to and fro within a very large
angle range. For the operating surgeon, this opens up a wide operating
field for the surgical instruments that are pushed through the device,
e.g. endoscopes, scissors, forceps and the like, for performing a
surgical intervention.

[0010] In practice, it has been found that, when surgical instruments are
extremely tilted and correspondingly oriented, they can have a tendency
to move the two joined- together proximal body portions slightly away
from each other as a result of the leverage exerted by the tilted
instrument. This leverage acts in a proximal end area of one proximal
body portion at the one side and in a distal end area of the adjacent
proximal body portion at the other side. It has been observed that
considerable gas losses occur as a result of gas escapes via the
longitudinal edges of the joined-together proximal body portions, even
when these are moved away from one another only by fractions of
millimetres.

[0011] A vaginal speculum is known from German Utility Model G 78 01 125.3
and is composed of two shell-shaped parts, wherein each part has a distal
body portion and, at an angle thereto, a proximal body portion.

[0012] In the area of the curvature, that is to say of the transition from
the respective distal body portion to the proximal body portion, the two
shell-shaped parts are firmly connected to each other by a joint. When
the distal body portions are placed against each other, the speculum can
be inserted into the vagina. When the proximal body portions are joined
together to form a hollow body, the already inserted distal body portions
then spread the vagina open. The physician can then make suitable visual
observations through the vaginal speculum designed as a hollow body.

[0013] A locking device is provided to ensure that, during the
observation, the two proximal body portions do not spread apart from each
other again as a result of the restoring force of the vaginal tissue.

[0014] On one of the two proximal bodies, the locking device has tabs
which protrude in a circumferential direction away from the longitudinal
edges thereof. The tabs, in a cross section perpendicular to the
longitudinal edges, widen in a wedge shape starting from the free end.
The tip of the wedge extends in a radial direction in view of the
longitudinal axis of the speculum. On the opposite proximal body portion,
recesses are provided on the inner or the outer face of the wall, into
which recesses the tabs fit and the wedge shape ensure a locking
engagement.

[0015] For this purpose, however, the geometry and shape of the tabs must
be such that they have a degree of elasticity allowing them to bend
radially, in order to be able to be driven into the recesses on the inner
or outer face of the wall surface of the other proximal body portion.

[0016] To release the locking mechanism, the operator has to exert a
strong radially inward pressure so as to slightly deform the hollow body
composed of the two locked proximal body portions, to an extend that a
wedge-shaped tab can escape from the recess on the wall. In the case of a
vaginal speculum, which is substantially larger than the device of the
present application and which has a considerable wall thickness and is in
most cases made of metals, an elastic tab construction of this kind and
recesses on the wall of the other proximal body portion can be provided.

[0017] In the case of substantially smaller hollow bodies with thinner
walls, like the device of the present application, such a construction
will not be able to work in a reliable manner. There would be the danger
of extremely tilted instruments causing deformations that allow the
wedge-shaped tab to escape from the recess on the inner wall.

[0018] It is therefore an object of the present invention to provide a
medical access device having a locking mechanism which prevents a release
of the locking by tilted instruments inserted in the medical access
device.

SUMMARY OF THE INVENTION

[0019] According to the invention, the object is achieved by a medical
access device for creating an access to a body for a minimally invasive
intervention, comprising a hollow body, assembled from at least two parts
having longitudinally extending edges, said at least two parts being
assembled along its respective longitudinally extending edges, each part
having a distal body portion and, at an angle to the latter, a proximal
portion, said distal body portions, when assembled along its edges,
result in a distal body with laterally outwardly standing proximal body
portions, and when moving said laterally outwardly standing proximal body
portions inwardly together along said edges and along a curved transition
area, a proximal hollow body results with laterally outwardly standing
distal body portions, a sealing cap fitted onto a proximal end of said
proximal hollow body and a locking mechanism locking said assembled
proximal hollow body portions, wherein said locking mechanism having at
least one hook projecting from an edge of a proximal body portion, said
hook having a nose extending from proximal to distal, and having a recess
in an edge joining said edge having said hook, said recess being cut into
said edge opposite to said hook and said recess opens to said hook, a
shape of said recess is in that, when moving said proximal body portions
inwardly together by rolling said edges to be joined in a first direction
along said curved transition area, said nose of said hook enters said
recess from proximal to distal without a relative movement between hook
and proximal part having said hook, and said recess blocks a movement of
said hook out of said recess in a direction perpendicular to surfaces of
said edges, thereby blocking a pulling away of joined edges, and wherein
said nose moves out of said recess, without a relative movement between
said hook and said proximal part having said hook, when moving said
joined proximal parts by rolling it in a second direction counter to said
first direction along said curved transition area.

[0020] The construction can be imagined as a kind of zip fastener in
which, during the zip movement, the locking elements enter the
corresponding recesses without necessarily requiring deformations of the
material. In the movement in the opposite direction, these locking
elements then escape again from the recesses. In other words, in the same
way as one closes a zip fastener in one direction and opens it in the
opposite direction.

[0021] During the rolling movement in the first direction, the approaching
longitudinal edges of the proximal body portions move towards each other.
The roll axes lie in the area of the curved transition area between
distal body portion and proximal body portion.

[0022] By providing a hook having a nose that extends from proximal to
distal, this nose can be driven from "above", i.e. from proximal to
distal, into a corresponding recess on the opposite edge, without
material deformations being necessary for this. The same also occurs in
the opposite rolling movement, that is to say when the access instrument
is to be removed again from the body, for which purpose the proximal body
portions are spread apart from each other again.

[0023] In the case of small structural parts, and also in the case of
structural parts made of plastic, the engagement of such a hook in a
recess can provide a sufficient resistance force with respect to
leverages acting on the two proximal body portions counter to the
direction in which they were joined together. This prevents a pulling
away of the edges joined together.

[0024] Thus, by means of simple and operationally reliable design
features, it is possible to withstand leverages and to avoid a loss of
gas, even in the case of very small structural parts.

[0025] It is possible to provide only one such hook. Alternatively,
several such hooks can be distributed along the longitudinal edges of the
proximal body portion.

[0026] A hook has the advantage of being an assembly aid when joining the
parts together. The hook differs from other projections, for example
knobs, and thus provides a clear orientation and therefore helps how one
part is to be placed onto the other part and joined to the latter. This
avoids an incorrect placement of the partial bodies in the sense of an
axial offset along the longitudinal edges.

[0027] The principal holding together of the two parts is achieved by the
cap fitted onto the proximal end of the joined-together proximal body
portions.

[0028] But, leverages forces tend to move away joined edges of the
proximal bodies the more these forces act away from the proximal end with
the cap fitted thereon.

[0029] In practical application, that is to say when surgical instruments
within the device are extremely tilted, the hook of the present invention
avoid the joined-together proximal bodies from being moved away from
another, particularly at areas rather away from the proximal end, and
thus to avoid the associated escape of gas.

[0030] In another embodiment of the invention, the hook is designed as a
nose which projects from the longitudinal edge of a proximal body portion
and which nose can be driven in and out of a recess in the opposite
longitudinal edge of the proximal body that is to be joined.

[0031] This measure has the advantage that the nose can be designed as a
relatively stable rounded body, which enters or leaves the recess in a
correspondingly smooth manner during the rolling movements. Even when
using relatively small structural parts, this nose can be made so stable
that it can also resist considerable leverages.

[0032] In another embodiment of the invention, the recess has an undercut,
behind which the nose can be moved.

[0033] This measure has the advantage that withdrawal of the hook can be
blocked by particularly simple structural means, namely by an undercut.

[0034] In another embodiment of the invention, the nose is configured in
such a way that, when it has entered the recess, it lies flush in the
recess.

[0035] This measure has several advantages. A flush contact between nose
and recess permits a relatively large bearing surface across which the
leverages can be distributed. At the same time, this has the advantage
that, as a result of the flush contact, a particularly gas-tight
connection to the outside is present in the area of the hook itself.

[0036] In another embodiment of the invention, the hook is designed as a
projection on the longitudinal edge of one proximal body portion, with at
least the wall thickness of the latter.

[0037] This measure has the advantage that the hook can be produced in a
particularly simple way from the point of view of manufacturing
technology. In the case of an injection-moulded part, the hook can be
produced as an integral component part of the wall of the distal hollow
body. Since this hook then projects from the longitudinal edge, it can
have at least the width of the wall thickness, or, if appropriate, it can
also be wider, such that a particularly resistant construction is ensured
that takes up considerable leverages.

[0038] In another embodiment of the invention, the recess is designed as a
material cutout through the entire wall thickness of the longitudinal
edge of a proximal body portion.

[0039] This measure in turn also has several advantages. Such a recess can
be produced very easily from the point of view of manufacturing
technology. In the case of an injection-moulded part it can be provided,
already during the original injection of the part. In the case of a body
made from metal, this recess can be easily milled out. Here too, it is
expedient to provide the recess through the entire material thickness,
such that intimate contact is then possible with a correspondingly shaped
hook.

[0040] In another embodiment, the hook is designed as an insertable part.

[0041] This measure has the advantage that the hook can initially be
produced as a separate structural part and can then be inserted and
embedded into the proximal body portion. This opens up the possibility,
for example, of this hook being made from materials other than the
material of the proximal body portion, in particular from more stable
materials. Thus, for example, the hook can be designed as a metal part
that can then be embedded into a body made of plastic, for example
integrated with the latter during the injection of the plastic part.

[0042] In another embodiment of the invention, the recess is formed in an
insertable part that can be inserted into the wall of a proximal body
portion.

[0043] This affords in principle the same advantage, that is to say that
the recess can be milled from a metal insert piece, and the latter can
then be embedded into a proximal body portion that has been otherwise
produced in advance. For example, this can also be done once again during
the plastic injection moulding of a plastic part.

[0044] If the body is made of metal, the recess can be easily produced by
removing material by milling.

[0045] In the case of the body being made of metal, so much material would
have to be removed from the solid material that the hook is shaped
protruding from the wall. This can be complicated and difficult.

[0046] Therefore, for example, the hook could be punched out as a
prefabricated punched part and then inserted into a corresponding recess
in the wall of the proximal body portion.

[0047] By virtue of the zip fastener principle, the hook can travel in and
out of the recess in a manner free from deformation.

[0048] It is thus possible, in the area of the hook, to avoid material
fatigue.

[0049] In another embodiment of the invention, at least one hook is
arranged in the area of a curvature in a transition area between the
longitudinal edges of a proximal body portion and the corresponding
distal body portion.

[0050] If it is arranged in the curved transition area between a distal
body portion and a proximal body portion, a hook provides an optimum
resistance force to the leverages that could cause an opening of the
joined edges. This is because, as is shown in the drawings, a tilted
instrument engages precisely in this curved area in order to exert these
leverages. The tilted instrument engages on the one hand on the proximal
end and on the other hand in the curved transition area of a part. The
lever action is thus resisted by the hook precisely at the location where
the leverages are applied directly.

[0051] It will be appreciated that the aforementioned features and the
features still to be explained below can be used not only in the cited
combinations but also in other combinations or singly, without departing
from the scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0052] The invention is described and explained in greater detail below on
the basis of a selected illustrative embodiment and with reference to the
attached drawings, in which:

[0053] FIG. 1 shows two parts of a device according to the invention,
which parts, in a first position for insertion of the instrument, are
assembled via the distal body portions,

[0054]FIG. 2 shows a side view of the medical device from FIG. 1, after
the latter has been introduced into a living body and the two proximal
body portions have been joined together and a proximal closure cap has
been fitted,

[0055]FIG. 3 shows a longitudinal section through the two joined parts
from FIG. 1, an intermediate state being depicted that corresponds to a
change-over from the pivoting position of FIG. 1 to FIG. 2;

[0056] FIG. 4 shows a much enlarged depiction of the area outlined with a
circle in FIG. 3,

[0057] FIG. 5 shows a sectional view which corresponds to FIG. 3 and in
which the proximal body portions, as can also be seen in FIG. 2, are
joined together,

[0058]FIG. 6 shows a greatly enlarged area of the area outlined with a
circle in FIG. 5,

[0059] FIG. 7 shows, in a cross section corresponding to the view in FIG.
5, the insertion of a rod-shaped instrument that is extremely tilted and
that tends to move away the two joined parts, and

[0060] FIG. 8 shows a greatly enlarged view of the area outlined with a
circle in FIG. 7.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0061] A medical device according to the invention shown in the figures is
designated overall by reference number 10.

[0062] FIG. 1 shows that the medical device 10 has a first part 12 and a
second part 14.

[0063] The first part 12 has a distal body portion 16, from which a
proximal body portion 18 protrudes at an angle. In the area of the
proximal body portion 18, the first part 12 is designed as a hollow body
having a shell shape and widening in the proximal direction.

[0064] The second body 14 also has a distal body portion 20 and,
protruding at an angle from the latter, a proximal body portion 24. This
proximal body portion 24 is also in turn designed as a hollow body having
a shell shape and widening in the proximal direction.

[0065] The size and the geometry of the two distal body portions 16 and 20
are such that, when they are joined together as shown in FIG. 1, they
form a distal body 32, which is approximately rod-shaped.

[0066] It will also be seen from FIG. 1 that the proximal body portion 18
has two longitudinal edges 24 and 26 extending lengthwise. Seen from the
proximal direction, these longitudinal edges 24 and 26 initially extend
approximately rectilinearly and, in a curved transition area 27, merge
into the corresponding rectilinear longitudinal edges of the distal body
portion 16.

[0067] The proximal body portion 22 of the second part 14 likewise has two
corresponding shaped longitudinal edges 28 and 30 which merge, via a
curvature 31, into the corresponding longitudinal edges of the distal
body portion 20. In the state of assembly shown in FIG. 1, the two
joined-together distal body portions 16 and 20 are placed in a living
body, for example at an incision in the abdominal wall and are driven
through this incision into the interior of the abdomen, in a manner that
is known per se and that is described in detail particularly in EP 2 228
024 A1 mentioned at the outset.

[0068] Thereafter, the proximal body portions 18 and 22, still spread
apart from each other, extend above the surface of the skin.

[0069] The two parts 12 and 14 lying on each other along its distal body
portions 16 and 20 are now folded such that the two proximal body
portions 18 and 22 are joined together to form a proximal hollow body 34,
as is shown in FIG. 2.

[0070] During this movement, the two proximal body portions 18 and 22 roll
over each other along their longitudinal edges 24, 26 and 28, 30 and over
a curved transition area 27 and 31, respectively.

[0071] A sealing closure cap 36, which has several functions, is then
fitted onto the proximal end of the joined-together proximal body
portions 18 and 22, as can be seen from FIG. 2.

[0072] In the state of assembly shown in FIG. 2, the cap 36 holds the two
body portions 18 and 22 together in the form of a proximal hollow body
34, since said cap is pushed over the proximal edge of the proximal body
portions 18 and 22. At the same time, it ensures a gas-tight seal in the
proximal direction. In the cap 36, there is at least one inlet 38 through
which a surgical instrument can be pushed through the cap 36 and the
distal hollow body 34 into the interior of the human or animal body, in a
manner known per se.

[0073] Mounted on the outer face of the proximal body portion 18 is a gas
attachment 40 via which a gas, in most cases CO2, can be supplied
for inflating the interior of the abdomen.

[0074] The cap 36 ensures a tight seal in the proximal direction.

[0075] Problem areas are sections of the joined longitudinal edges 24 and
30 of the proximal body portion that bear on each other, and also the
corresponding edges 26 and 28 bearing on each other which sections are
relatively far away from the cap 36. In order to ensure a seal that is as
gas-tight as possible here, a row of toothing features is provided on the
longitudinal edges 26 and 28, as can be seen in particular in FIGS. 3 and
4. It will be seen in particular from the enlarged view in FIG. 4 that
knobs 44, 44' protrude from the longitudinal edge 28 and can be fitted
into opposite depressions 43, 43', respectively, on the longitudinal edge
26.

[0076] In the more proximal area, a tongue 45 protrudes from the
longitudinal edge 28 and can fit into a longitudinal groove 47 (not
visible in detail here) on the opposite edge 26.

[0077] This structure not only leads to a targeted and guided rolling
movement of the longitudinal edges 28 and 26 when the proximal body
portions 18 and 20 are joined together but also at the same time provides
toothing features which block a release of the two proximal body portions
18 and 22 transversely with respect to the longitudinal extent of the
longitudinal edges.

[0078] It will be seen in particular from the enlarged view in FIG. 4
that, in the curved transition area 31 of the longitudinal edge 28 of the
proximal body portion 22, a hook 48 protrudes from the latter and can be
fitted into a corresponding recess 46 on the opposite longitudinal edge
26 of the proximal body portion 18 when the longitudinal edges 26 and 28
are moved towards each other in a first direction, as is indicated by the
two arrows 51 in FIG. 3, when they are being joined together. The hook 48
has a nose 54, which extends sloping in the distal direction.

[0079] The recess 46 has a corresponding undercut 58. During the rolling
movement and joining together, the nose 54 of the hook 48 now runs from
distal to proximal into the recess 46 and behind the undercut 58, as can
be seen from the change from FIG. 4 to FIG. 6.

[0080] No material deformation is necessary for this. Rather, during the
rolling movement along the curved transition area 31 or the curved
transition area 27, the nose 54 of the hook 48 runs snugly into the
recess 46 and behind the undercut 58.

[0081] For removing the device 10 after a surgical action, the cap 36 is
removed and the proximal body portions 18 and 22 are spread away from one
another with a rolling movement along its edges in a second direction
counter to the first direction. The distal body portions 16 and 20 join,
as shown in FIG. 1, and the device can be removed from the living body.

[0083] In the state shown in FIG. 2 and in FIGS. 5 and 6, the hook 48 thus
blocks a movement of the two joined-together proximal body portions 18
and 22 counter to the direction of joining together, as indicated by
arrows 55 in FIG. 6. This blocks a pulling away of the joined edges 24
and 30 as well as edges 26 and 28 along a direction of arrows 55 which is
perpendicular to the surface of the edges.

[0084] FIGS. 7 and 8 show a situation in which leverages occur that are of
such a kind that they tend to move the joined-together longitudinal edges
26 and 28 slightly away from each other also when the cap 36 is fitted.

[0085] FIG. 7 shows that a rod-shaped instrument 60 is inserted in and
through the device and that the instrument 60 is extremely tilted.

[0086] It thus abuts, at the proximal end, against the inner upper
proximal edge, for example of the proximal body portion 22.

[0087] This strongly tilted instrument 60 strikes the distal end region of
the proximal body portion 18 of the body part 12 and tends to lever it
open, particularly in the area of the curvature 27, i.e. move it away
from the longitudinal edge 28.

[0088] If such a leverage is not applied, the restoring force of the
abdominal wall 64 through which the instrument 10 according to the
invention is pushed into a living body is normally sufficient to ensure
an adequate pressing force of the two parts 12 and 14 in this area in
order to avoid gas losses.

[0089] However, if an instrument 60 is tilted as strongly as is indicated
in FIG. 7, there is the danger of the two parts 12 and 14 being moved
apart.

[0090] It will be seen from the enlarged view in FIG. 8 that the nose 54
of the hook 48, which has been moved behind the undercut 58, blocks this
movement along arrows 55 as shown in FIG. 6. This works particularly if
it is arranged at this location of the curved transition area.

[0091] Of course, this structure also provides a blocking effect if the
instrument 60 is tilted in the opposite direction.

[0092] Only one such hook is shown in the illustrative embodiment, but it
is also possible for several such hooks to be provided in the area of the
curvature in the direction of the proximal end if it is feared that
extremely strong leverages can be exerted because of the inserted
instruments.

[0093] It is indicated in FIG. 4 that the hook 48 can be designed as a
separate part 50 that is fitted or embedded into the wall of the proximal
body portion 22 in the area of the longitudinal edge 28. For this
purpose, the hook has a cornered insert piece 52 that is inserted with a
firm fit into a corresponding recess or milling. This can be done by
screwing or soldering, or also by injection in a plastic injection
moulding operation.

[0094] Correspondingly, a part 56 that has the recess 46 is fitted or
embedded on the opposite longitudinal edge 26. This part is then inserted
or anchored correspondingly.

[0095] This opens up the possibility, for example, of producing the parts
12 and 14 from an inexpensive plastic material in a single injection
moulding operation. To effectively withstand excessive leverages and to
take up considerable forces, the parts 50 and 56 can then be produced
from more resistant material, e.g. metal, and used as insert pieces. This
can already take place, for example, in the original injection moulding
operation.

[0096] In this way, a single hook of this kind can already be sufficient
to prevent a moving away of joined edges due to leverages.

[0097] It is of course also possible for the hook and recess, produced as
parts made from plastic, to be produced directly in the injection
moulding operation.

[0098] In the case of instruments made of metal, the recess can be made by
a simple milling operation, but the hook would then have to be shaped
from the solid material or correspondingly fitted. In this respect, a
person skilled in the art has many possible options available for
providing structures according to client requirements.

[0099] It can be seen in particular from FIG. 8 that the hook 48, or the
nose 54 thereof, corresponds exactly to the contour of the recess 46 and
is thus received flush inside the latter.

[0100] This additionally contributes to a gas-tight seal in this area,
specifically against passage of gas transverse to the longitudinal
direction of the longitudinal edges 26, 28 and 24, 30 in the area of the
hook 48.

Patent applications by Martin Oberlaender, Engen DE

Patent applications by Michael Sauer, Tuttlingen DE

Patent applications in class With cooperating retracting members

Patent applications in all subclasses With cooperating retracting members